I have a lot of friends that will use someone else's makeup or used make up. I personally think its gross and stupid even if you know the person you are sharing the makeup with you can get something. Makeup should be thrown out every couple of months max. I throw my eye makeup out every 4-6weeks.
That is GROSS! If you're not careful, you could end up getting an infection from the used makeup. I don't know why anyone would want someone's old makeup. The underwear, well, there are sickos that like to buy other people's panties!
I personally wouldn't,sounds icky, but maybe a pump bottle foundation wouldn't be all that "gross". But something someone literally touches on their face, then re touches (with a brush or anything) it skeeves me out about the sample items on display in sephora (i get you're not supposed to touch the products and use certain things, but ehhhh.) and when they do your make up they use certain brushes on multiple people.